Our studies are directed toward the determination of the three dimensional structure of immunoglobulins and specific antibodies and the understanding of the structural basis of antibody function. The detailed three dimensional structures of two Fab fragments, several Fab-ligand complexes and the pfc's fragments of guinea pig IgG1 will be studied by X-ray diffraction techniques. A search for hapten-specific induced antibodies suitable for structural studies will be continued using cell hybrids.